What would be the best way to test these to see how much, or if, they are any better than my wireless adapter?

Edit:
Router is a netgear 3700v3 and the wireless adapter is an ENCORE ENEWI-2XN45 Wireless N300 rated for 300mbps. The router, sending computer, and recieving computer are all gigabit. Distance between the powerline adapters is 3 floors.

To test latency I used the command ping 192.168.1.1 -n 100

Wireless latency:
Minimum = 1ms, Maximum = 59ms, Average = 5ms

Powerline latency:
Minimum = 3ms, Maximum = 5ms, Average = 3ms

I did a load test with a 964mb mp4 video file.The sending computer was wired into the router during both load tests Over powerline it cycled from 3 megabytes/s to 5 megabytes/s in a very consistent manner producing a very nice speed graph in windows 8. Over wireless the speed ranged from a low of 200 kilobytes/s to a peak of 3 megabytes/s but having an average of 1 megabyte/s. The load test showed much more consistent speeds along with higher speeds over powerline.

The powerline adapter was much much more consistent as I expected. Just as consistent as if I was directly plugged into the router. I find it surprising though that the wireless had the lower minimum latency, although by 2 milliseconds. Speeds were not as good as being direct to the router, but still faster than wireless. Overall I think powerline adapters are far superior to wireless.